Enzymatic and soil burial degradation of corn starch/glycerol/sodium montmorillonite nanocomposites

In this study, effects of glycerol (10, 20, and 30 wt%) and Sodium Montmorillonite (Na-MMT) (0%, 2.5%, and 5%) contents on the degradation of corn starch polymers were investigated. Films were prepared by casting corn starch solution using a modified method to enhance the nanoclay distribution. Biodegradability studies were performed by enzymatic and burial tests using pristine and enriched soils. The biodegradability of samples in pristine soil was faster, and all samples were fully degraded in 6 months. The effect of nanoparticles on the mass reduction in degradation was more pronounced than that of glycerol. In all glycerol concentrations, Na-MMT addition increased tensile strength. FTIR tests showed that degradability was related to glycerol leaching at first and then cleaving of α-1,4 bonds of starch, indicating the action of α-amylase produced by soil microorganisms. Good agreement between soil burial tests and enzymatic degradation was observed. An optimum Glycerol/Clay ratio was observed at which d-spacing and mechanical properties were maximum.